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O. E. TAPT.

SURVEYING INSTRUMENT.

No. 311,386. Patented Jan. 27, 1885.

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(No Model.)

O.E.TAPT.

SURVEYING INSTRUMENT.

No. 311,386. Patented Jan. 27, 1885.-

Q EN Unirrnn Smarts PATENT FFMJE.

CHARLES E. TAF'I, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONEHALF TO CHARLES V. HICKOX, OF SAME PLACE.

SURVEYING INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 311,386, dated January 27, 1885.

(No model.)

To all whom it may concern.-

Be it known that 1, CHARLES E. TAFT, a citizen of the United States, residing at Ohicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Surveying-Instruments, which are fully set forth in the following specification, reference being had to the accompanying drawings, in Which Figure 1 represents a side elevation of the leveling-rod; Fig. 2, a plan section of the same, taken on the line a: 00, Fig. 1; Fig. 3, a section of the same,on an enlarged scale, taken on the line yy, Fig. 1; Fig. 4, a detail front elevation of the upper portion of one part of the leveling-rod; Fig. 5, a perspective view,on an enlarged scale, of the sliding target of the leveling-rod; Fig. 6, a side elevation of the transitinstrument; Fig. 7, a front elevation of the same; Fig. 8, a transverse section of the same, taken on the line 1) c, Fig. 6, and on an enlarged scale; Fig. 9, a longitudinal section of the same, taken on the line to to, Fig. 6, on an enlarged scale; Fig. 10, a transverse section of the same, taken on the line 2 z,Fig. 6, on an enlarged scale; Fig. 11, a plan section of the same, taken on the line a a, Fig. 6; Fig. 12, a detail section of the same, taken on the linet t, Fig. 6; and Fig. 13, an elevation showing the instrument in position for actual use.

My invention relates to instruments for making measurements under ground in tunnels,or surveying in mines or other like locations where the work is to be done below the surface and in the absence of sunlight.

The invention also relates to certain improvements in the construction of the transitinstrument and the stadium or leveling rod, whereby accurate and reliable work may be accomplished.

I will proceed to describe in detail one way in which I have carried out my invention in practical form, and will then point out definitely in the claims the special improvements which I believe to be new and wish to protect by Letters Patent.

In the drawings, A represents the stadium or leveling rod, which consists of two rods, a a, exactly parallel and about half an inch apart, connected firmly together at top and bottom by cross-strips, in the bottom one of which is set a pin, a directly in the center, so as to indicate the exact center of the space between the rods. These rods may be of any desired form in crosssection, and one of them has suspended within it a small plumb'bob, B, preferably at the upper end thereof, and made visible bya hole drilled through the rod. The other rod, a, is carefully graduated into feet and decimal divisions, orinto the divisions of the meter, and at the top thereof a wire, C, is stretched between the rods at the exact zero division. A target, D, is fitted to slide on the rods, and is provided with the clamping-screw d, by which it may be fastened to the rods at any point. It is also provided with avernier, E, by which to read the smallest division of the graduated scale on the rod. An opening, cl, is cut through the target opposite the space between the two parallel rods, through which a light located behind the stadium can be seen, and across this opening is stretched a wire, F, to mark the zero of the target. The plumbbob suspended within the tube is attached to some kind of an adjustable fastening to provide for the removal of the bob or the adjustment of the suspending-cord. In the drawings this is a screw stopper or knob, 11, which is fitted to a threaded bushing in the top of the tube.

The transit-instrument consists of a telescope, G, of ordinary construction in general features, which is mounted on a tripod, H. The telescope is provided with two horizontal cross hairs or wires, 9, in its focus, which are accurately adjusted at such a distance apart that they will exactly cover a certaindistance on the stadium-rod when it is held at any certain distance off-as, for instance, the wires may be so adjusted as to cover a length of three feet on the rod when it is set three hundred feet from the instrument. The adjustment of the wires being known, any intermediate distance from the instrument is at once shown by the length on the rod covered by thereof, as shown in Figs. 9 and 10 of the drawings- This permits the sight through the reflector, while at the same time the annular reflecting-surface will be sufficient to light up the cross-hairs. Below the telescope is arranged a graduatedeircle, J, of any usual construction, and for the usual purpose, and from the plate of this circle rise posts K, which support the telescope, which is pivoted at its front end to one of the posts, and at the other end is connected to the other post by any ordinary means which will provide for vertical adjustment. Light is admitted to the reflector within the tube of the telescope through an opening, 1', in the side thereof, in which a plain lens is fitted. The stadium-rod is of course held by an assistant, and is made visible by a lamp carried by him.

The mode of using these devices is illustrated in Fig. l3 of the drawings. The assistant first sets up the stadium-rod at the required point, and then raises his lamp until it is seen by the observer at the upper cross-hair. This crosshair is then made to exactly coincide with the zero-wire on the stadium-rod. The assistant then lowers his lamp until it is seen by the observer at the lower cross-hair, and then moves the target on the rod until the cross-wire on the target is seen to be exactly over the lower cross-hair. The target is then clamped to the rod, and the distance read. ofi that the crosshairs cover, which is from the wire on the rod to the wire on the target, and from this distance may be calculated the distance between the transitinstrument and the stadium -rod. The space between the two rods of the stadium permits light to shine through between the same from a lamp behind, which enables the targct-wire to be seen through the opening in the target, and to be accurately adjusted, as described above.

The use of the graduated circle in determining angles and courses will be understood, as it is the same as usual.

Having thus described my invention,.what

I claim as new, and desire to secure by Letters Patent, is- 1. A stadium-rod having graduations thereon, and composed of two parallel rods or bars connected at' top and bottom, and arranged with a narrow space between them, in combination with a centering-pin set in the bottom connection at the exact center of this space, substantially as and for the purposes set forth. 2. The stadium-rod A, consisting of the two parallel bars a a, arranged a slight distance apart, and one of which is graduated, in combination with the cross-wirelocated at the zer0- point of the graduated scale, and the sliding target D, provided with the opening at, c'oinciding with the opening between the rod-bars and the cross-wire across the said opening d, substantially as and for the purpose set forth. 3. The telescope provided'with two hori zontal wires, in combination with the stadiunr rod, the cross-wire arranged at zero-point on the stadium-rod, and the sliding target provided with a central opening and a wire stretched across the same, all constructed and operating substantially as and for the purposes set forth.

v CHARLES E. TAFT. Vitnesses:

A. M. Bns'r, Tnonas H. PEASE. 

